STMicroelectronics RHFAC14K1

Overview

RHFAC14K1 from STMicroelectronics is a radiation-hardened hex Schmitt-trigger inverter in the 54AC logic family, designed for aerospace and high-reliability systems requiring TID immunity up to 300 krad(Si), SEL immunity up to 110 MeV·cm²/mg, and operation from –55 °C to +125 °C. It supports CMOS-level input thresholds (2–6 V supply), delivers rail-to-rail output swing, and is housed in a QML-V qualified ceramic Flat-14 hermetic package.

For engineers reviewing the RHFAC14K1 datasheet, RHFAC14K1 pinout, RHFAC14K1 application, or RHFAC14K1 equivalent, this device is selected for critical timing conditioning, noise-immune signal inversion, and digital interface buffering in satellite command/data handling, radiation-tolerant FPGAs, and deep-space avionics where latch-up immunity and wide temperature stability are mandatory.

Technical Context

The RHFAC14K1 implements six independent Schmitt-trigger inverters with hysteresis (typically 0.8 V at V_CC = 3 V), enabling robust noise rejection on slow or noisy input signals. Its input structure includes clamp diodes rated for ±20 mA, and outputs drive rail-to-rail with 3-state capability disabled (non-bus version).

It belongs to the AC-series subset optimized for low-power, high-speed CMOS operation across 2–6 V, distinct from the TTL-compatible ACT-series (4.5–5.5 V). Radiation hardening is achieved via process-level design (AMK6 diffusion line) and wafer-level qualification per MIL-STD-883 cond A.

Key Specifications

Pinout & Package

Ceramic Flat-14 hermetic package (QML-V qualified), 14-terminal surface-mount outline with grounded metallic lid option. Dimensions: 9.27–9.73 mm × 6.19–6.50 mm × 2.31–2.72 mm (L × W × A), 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Schmitt-trigger inverter applications.

Compared with RHFAC14K1, the 54AC14 offers cost savings without radiation certification, while RHFAC14A trades speed for lower quiescent current-making RHFAC14K1 optimal for flight-critical, speed-sensitive interfaces demanding full QML-V compliance.

Availability

RHFAC14K1 is available at Aetrix Electronics and suitable for spacecraft telemetry conditioning, satellite command decoding, rad-hard FPGA configuration, and launch vehicle avionics bus isolation requiring stable component supply under extended lead times and strict lot traceability.

Supply support for RHFAC14K1 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader specializing in automotive, industrial, and aerospace-grade ICs, with decades of heritage in radiation-hardened technology and QML-V manufacturing.

RHFAC14K1 belongs to the 54ACxxxx rad-hard logic series, engineered specifically for mission-critical space electronics where immunity to total ionizing dose, single-event effects, and extreme thermal cycling is non-negotiable.

FAQ

Is RHFAC14K1 pin-compatible with commercial 74AC14 devices?

No. While logic function and pin numbering match, RHFAC14K1 uses a ceramic Flat-14 package with different mechanical dimensions, thermal characteristics, and hermetic sealing. Commercial 74AC14 parts use plastic DIP or SOIC packages and lack radiation hardening, making them unsuitable for space use even if footprint appears similar.

What is the maximum operating frequency of RHFAC14K1 at 3.3 V?

At V_CC = 3.3 V and –55 °C to +125 °C, the typical propagation delay is 7 ns per inverter, supporting reliable operation up to ≈35 MHz for clean square-wave inputs. System-level frequency is limited by input transition time (dt/dv ≤ 8 ns/V) and load capacitance; derating is required above 25 MHz in high-radiation or high-temperature conditions.

Does RHFAC14K1 require external decoupling capacitors?

Yes. Each V_CC pin must be decoupled with a minimum 100 nF X7R ceramic capacitor placed within 10 mm of the pin, plus a 1 µF bulk capacitor per package. This is mandatory to suppress switching noise and maintain stable operation under radiation-induced supply transients and thermal cycling.

Can the metallic lid be left floating, or must it be grounded?

The lid may be either floating or grounded per design requirements. In grounded-lid versions (e.g., RHFAC14K1-G), the lid connects internally to Pin 7 (GND); in floating-lid versions, no internal connection exists. Grounding improves EMI shielding and thermal conduction but requires mechanical grounding to PCB ground plane.